The present invention relates to an apparatus for detecting the direction of a moving vehicle in which a geomagnetic azimuth detector and a turning angle detector are combined.
Heretofore, apparatuses utilizing geomagnetism, for example, the so-called magnetic compass, utilizing the rotation of a magnet, have been often employed in order to detect and indicate the traveling direction of a moving vehicle such as automobile. In such apparatuses, however, a considerable reading error develops due to the vibration or turning of the moving vehicle. As apparatuses free from the disadvantage, there have been devised various devices which apply a method of directly converting a geomagnetic azimuth into an electrical signal, in other words, a flux-gate magnetometer, or which utilize a magnetosensitive device such as Hall device and magnetoresistor.
However, insofar as the method of detecting the geomagnetism is relied on, a precise azimuth signal cannot be obtained in a region where a magnetic disturbance occurs, such as an intense-field region.
As other methods for detecting the direction of a moving object, dynamic turning-angle detecting methods have been devised.
Among apparatuses employing the methods, the most precise apparatus is a gyro-compass. The gyro-compass, however, is very expensive and difficult to be used in mass-produced vehicles, such as automobiles. Besides, for the overland traveling, it is also possible to detect the turning angle of steering or the like. With this method, however, an accumulated error, due to the use for a long term, may become great. In the dynamic turning-angle detection, the most serious disadvantage is that the geographic azimuth cannot be detected at all.